Electromagnetic heads, flexures, gimbals and actuators formed on and from a wafer substrate

ABSTRACT

Devices for reading or writing electromagnetic information include a wafer substrate piece disposed between an electromagnetic transducer and an electrostrictive or piezoelectric actuator. The substrate piece is shaped as a rigid body adjoining the transducer and as a flexible element connecting the body and the actuator. To fabricate, at least one electrostrictive layer and many transducers are formed on opposite sides of a wafer that is then cut into rows containing plural transducers. The rows are processed from directions generally normal to the wafer surface upon which the transducers were formed, by removing material to form a head, flexures and a media-facing surface on the head. Conductive leads are formed on a back surface of flexures connecting the transducer with drive electronics. The flexures are aligned with forces arising from interaction with the media surface and from seeking various tracks, reducing torque and dynamic instabilities and increasing actuator access time.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit under 35 U.S.C. §119(e) ofProvisional Patent Application Ser. No. 60/219,994, filed Jul. 21, 2000,by the same inventor and having the same title. The disclosure of thatProvisional Patent Application is incorporated by reference herein.

TECHNICAL FIELD

The present invention relates to electromagnetic heads, gimbals andflexures for holding such heads, as well as to actuators that may beused for positioning such heads.

BACKGROUND OF THE INVENTION

Conventional electromagnetic heads such as those employed in disk ortape drives are formed in a plurality of thin films on a substrate,after which the substrate is cut or diced. In this manner a single wafermay yield many hundreds of heads. After formation, each head may then beattached to an arm for positioning the head adjacent the media. The armmay be attached to the head by flexure or gimbal elements, which allowthe head to adjust relative to the media surface, compensating forimperfections in that surface or other dynamics.

Conventional disk drives have an actuator which positions a pair of sucharms or load beams adjacent each spinning disk, the arms each holding asmaller flexure and gimbal that is mechanically connected to the head.Twisted wires have traditionally provided electrical connections betweensuch heads and drive electronics, the wires held by tubes or crimpsalong the load beam and soldered to electrical bond pads on the head.Recently, so called wireless suspensions have been implemented, whichuse conductive leads that run along flexures and gimbals to providesignal communication with the head, although connections between theleads and conductive pads on the head are conventionally made by wirebonding. These wireless suspensions are typically laminated and includelayers of stainless steel for strength, with conductors such as copperisolated by plastic or other dielectric materials.

The conductive traces still need to be bonded to pads on the head, butusually impart less mechanical uncertainty to the gimbal mechanism thantwisted wires, and can be connected by machines for wire stitching. Inorder to reduce the size of such gimbals and flexures, U.S. Pat. No.5,896,246 to Budde et al. proposes fabricating a magnetic headsuspension assembly from a silicon structure using etching techniques. Asimilar idea is described in U.S. Pat. No. 5,724,015 to Tai et al.,which appears to have resulted from an industry-government partnershipexploring the fabrication of head suspensions from silicon parts.

U.S. Pat. No. 5,041,932 to Hamilton goes a step further, fabricating theentire head and flexure from thin films that are then lifted from thewafer on which they were formed. The resulting integrated head andflexure, which is generally plank-shaped, does not have a gimbalstructure for conforming to the media, instead relying on ultralightmass and continuous contact for mechanical stability, durability andhigh resolution. The thin films of Hamilton's flexhead are formed inlayers that are primarily parallel to the media surface, unlike mostconventional disk heads, which are formed in layers that end up on atrailing end of the head, extending perpendicular to the media surface.

Recent years have witnessed dramatic growth in the use ofmagnetoresistive (MR) sensors for heads, which sense magnetic fieldsfrom a disk or tape by measuring changes in electrical resistance of thesensors. Care is usually taken to avoid sensor contact with a rapidlyspinning rigid disk, as such contact may destroy the sensor or createfalse signal readings. In order to increase resolution, however, currentproduction heads may fly at a height of one micro-inch from the disksurface. MR sensors are typically formed along with inductive writetransducers in thin films on a wafer substrate. After formation, thewafer is diced into sliders each having thin film inductive and MRtransducers on a trailing end, the sliders' length determined by thewafer thickness.

As heads become smaller, connection of even modern wireless suspensionsbecomes difficult and may add undesirable mechanical complexities to thegimbal area. Moreover, MR sensors can be delicate and require at leasttwo extra leads that must be connected to the drive electronics, addingto connection difficulties. Additionally, as heads are required to flycloser to the media and provide quicker access time to various tracks onthe disk, mechanical challenges increase.

Further, as a means for increasing the density at which bits are storedon a media surface, the spacing between adjacent recording tracks andthe width of each track may be reduced to a level not accuratelyaccessible with conventional actuators. As a result, a number of designsfor dual actuators have been proposed, typically including aconventional rotary actuator for large-scale positioning and amicroactuator disposed nearer the head for small-scale positioning. Someof these proposed microactuators, however, interfere with flexure andgimbal mechanics, such as devices that rotate a head relative to anattached flexure. Other proposed microactuators introduce other errors,for example by using mechanical pins or other mechanisms for pivoting.

SUMMARY OF THE INVENTION

In accordance with the present invention integrated head, flexure,gimbal and/or actuator devices formed on and from a wafer substrate aredisclosed. Conventional problems of connecting the head to the flexureand/or gimbal are reduced or eliminated, as all of these elements may bemade on and from the same wafer on which the transducer is formed. Thetransducer layers may be oriented generally perpendicular to the mediasurface, affording employment of the most proven high-resolutiontransducer designs. Electrical leads may also be formed on theintegrated flexure and/or gimbal in contact with leads of the head.Additionally, a microactuator may be formed on an end of the structurefurthest from the transducer layers, providing a relatively simplemechanism for greatly increasing the accuracy with which the transduceris positioned adjacent media tracks and increasing track density.

Heads formed in accordance with the present invention can be madethinner and do not need a large area on the trailing surface for bondingpads, reducing their mass and moment arms. The gimbals and flexures canbe more closely aligned with forces arising from interaction of the headwith the disk surface and from seeking various tracks, reducing torqueand dynamic instabilities. Alignment of a plane of the flexures betweenthe actuator and the head greatly reduces low frequency vibrations dueto actuation, as motion induced by the actuator is confined to a stiffin-plane direction as opposed to a flexible out-of-plane direction ofthe flexures. Spacing between disks can be reduced due to the thinnerheads and lower profile gimbals and flexures. The heads may be operatedin continuous or intermittent operational contact with the media, or maybe designed to avoid such contact during operation. This brief summarymerely lists a few possible features of the invention, which isdescribed in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of a media-facing side of a device of the presentinvention including an integrated head, gimbal and flexure.

FIG. 2 is a side view of the device of FIG. 1 interacting with a mediumsuch as a rigid disk.

FIG. 3 illustrates some initial steps in forming the head of FIG. 1.

FIG. 4 shows the partially formed head of FIG. 3 during formation on awafer substrate.

FIG. 5 shows a row cut from the substrate of FIG. 4, the row includingthe head of FIG. 3.

FIG. 6 shows the formation of air bearing rails and pads of themedia-facing surface of the head of FIG. 1.

FIG. 7 shows the masking of the head of FIG. 1 during material removalthat shapes the media-facing side of the gimbal and flexure of FIG. 1.

FIG. 8 shows the formation of a non-media-facing side of the device ofFIG. 1.

FIG. 9 shows a disk-facing side of another embodiment of the presentinvention.

FIG. 10 shows an opposite side from that shown in FIG. 9, including anamplifier attached to a load beam and connected with leads disposed onthe flexure and gimbal that are connected with the head.

FIG. 11 is a side view of the suspension elements of FIG. 9,illustrating a flexure located close in Z-height to the center of massof the head.

FIG. 12 is a side view similar to that of FIG. 11 but with a load beamhaving a tongue that extends over the head.

FIG. 13 is view of a trailing end of the device of FIG. 9.

FIG. 14 is view of a trailing end of the device of FIG. 9, including anamplifier formed on the head.

FIG. 15 is a cross-sectional view of an initial stage in forming theamplifier of the head of FIG. 14.

FIG. 16 is a cross-sectional view of the amplifier of the head of FIG.14, prior to the formation of a transducer on the head.

FIG. 17 is a media-facing side of a media-contacting embodiment of thepresent invention including an integrated head, gimbal and flexure.

FIG. 18 is a side view of the embodiment of FIG. 17 attached to a loadbeam that extends over the head and holds an amplifier.

FIG. 19 is a top view of the head, flexure and beam of FIG. 18, with theamplifier connected with leads disposed on the flexure and gimbal thatare connected with the head.

FIG. 20 is a view of media-facing side of a device of the presentinvention including an integrated head, gimbal, flexure and actuatorhaving a common electrode.

FIG. 21 is a side view of the device of FIG. 20 attached to a load beam.

FIG. 22 is the device and load beam of FIG. 21 viewed from an oppositeside as that shown in FIG. 20.

FIG. 23 is an outline view of media-facing side of a device of FIGS.20-22, with motion induced by the actuator joining the device and loadbeam.

FIG. 24 is a view of media-facing side of a device of the presentinvention including an integrated head, gimbal, flexure and actuatorhaving laterally spaced pairs of electrodes and attached to a load beam.

FIG. 25 is a side view of the device and load beam of FIG. 24.

FIG. 26 is a cross-sectional view of the formation of layers for alaminated actuator.

FIG. 27 is a top view of the layers of FIG. 26 formed into a laminatedactuator on a substrate that may be part of a head and flexure device.

FIG. 28 is a top view of the layers of another embodiment of a laminatedactuator connected to a substrate that may be part of a head and flexuredevice.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a media-facing side of a device 30 of the present inventionincluding an integrated head 33, gimbal 35 and flexure 38. The head 33includes an inductive transducer 40 and a magnetoresistive (MR)transducer 44, although other types of transducers may alternatively beemployed. As will be explained in greater detail below, the transducers40 and 44 are formed along with many other similar transducers on awafer substrate, after which the wafer is cut into rows each containinga number the transducers, and the rows are then processed from anotherdirection to form the integrated head 33, gimbal 35 and flexure 38.

A media-facing surface 46 of the head 33 includes rails 48 and 49 and atransducer-containing pad 50 that are designed to be closer than theremainder of the media-facing surface to the media during operation. Therails 48 and 49 and pad 50 may project about a micron or less from theremainder of the bearing surface 46. The gimbal 35 and flexure 38 aremuch thinner than the head, in order to increase flexibility of thegimbal and flexure. The gimbal 35 and flexure 38 may also be disposedfurther from the media than the media-facing surface 46 of the head 33,in order to remove them from interactions with the media or gases orliquids that travel with the media.

FIG. 2 shows a side view of the device 30 interacting with a media 60such as a rigid disk, a cross-section of which is shown. The media 60has a surface 63 and a media layer 66 formed over a substrate 68, and istravelling relative to the head 33 in a direction indicated by arrow 70.The head 33 may have a thickness in a direction perpendicular to themedia surface 63 that is on the order of 100 μm, whereas the gimbal 35and flexure 38 may have a thickness of only 5 μm-50 μm in thatdirection. For clarity, the direction perpendicular to the media surfaceis defined as the Z-direction, whereas a direction perpendicular to theZ-direction and substantially aligned with the direction of media travelis defined as the X-direction, while a direction orthogonal to the X andZ-directions is defined as the Y-direction. As is conventional in thedisk drive industry, a distance measured along the Z-direction away fromthe media may be referred to as a Z-height.

The gimbal 35 and flexure 38 are much closer in height to the center ofmass of the head 33 than is conventional, reducing dynamic instabilitiesthat otherwise can occur during track seeking and settling, andtherefore reducing access times. This alignment of suspension height andhead mass is due in part to having the top surface of the flexurealigned with the top surface of the head, whereas conventionalsuspensions have their bottom surface located above the top of the headand tapering down to meet the head top surface at bond areas. Also, thehead of the present invention can be reduced in height, since largeareas on the back of the slider are not needed for providing conductiveconnections with the suspension. Having a relatively low gimbal 35 andflexure 38 also helps to align those suspension members with forcesgenerated by interaction with the disk 60, whether due to contact ornear contact. This helps to achieve lower flying heights and avoidscrashes that may otherwise occur due to wobbling sliders whose cornersplow into the disk.

Referring additionally to FIG. 1, a plurality of conductive leads 52,53, 54 and 55 are disposed in the flexures 38, connected with transducerleads 56, 57, 58 and 59 disposed in gimbal elements 35. As will beexplained in more detail below, transducer leads 56, 57, 58 and 59 canbe defined during formation of transducers on a wafer to provideguidance during row bar processing for the formation of gimbals 35 andflexures 38 of a desired thickness. Conductive bond pads 74, 75, 76 and77 provide connections for device 30 with a load beam 80. Load beam 80,which may be made of conductive and insulative laminates, has anextending tongue 85 that may include a dimple that provides a fulcrumfor head 33, and tongue may extend past the head in the X-direction,although not shown in FIG. 2. Such a dimple may be formed by pressing,for the situation in which the tongue 85 contains stainless steel, forinstance, or by deposition and/or patterning for the situation in whichthe tongue 85 is formed by similar deposition and/or patterning.Alternatively, a protrusion 88 may be formed on a back surface of thehead 33, for example by deposition or by etching of other portions ofthat back surface, as described below.

In FIG. 3 some initial steps in forming the head 33 are shown. The head33 is formed on a wafer substrate 100, also shown in FIG. 4, that may bemade of alumina (Al₂O₃), alumina titanium carbide (Al₂O₃—TiC), silicon(Si), silicon dioxide (SiO₂), silicon carbide (SiC) or other knownmaterials, the head being mass-produced along with hundreds or thousandsof other heads. Substrates containing silicon may be preferred for theirability to be deeply, quickly and controllably etched. Also, asdescribed below, transistors may be formed on the substrate adjacenttransducers 40 and 44 for signal amplification, for which silicon may beadvantageous. The dimensions of the head, flexure and gimbal elementsare determined based upon known characteristics of the materials formingthe substrate and film layers. Note that etching or other removalprocesses used for patterning the head, flexure and gimbal elements arecontrollable in three dimensions rather than two, affording designflexibility.

After polishing and preparing a surface of the wafer substrate 100, afirst magnetically permeable layer 102 is formed of a material such asPermalloy (NiFe), which will function as a magnetic shield. A first readgap layer 105 of a nonmagnetic, electrically insulating material such asalumina, silicon dioxide or diamond-like carbon is then formed, on topof which the magnetoresistive (MR) sensor 44 is formed. The MR sensor 44may be an anisotropic magnetoresistive (AMR) sensor, spin valve (SV)sensor, giant magnetoresistive (GMR) sensor, spin tunneling (SP) sensoror other known sensors, the details of which are known in the art andomitted here for conciseness. After the MR sensor 44 has been formed theleads 57 and 59, shown in FIG. 1, are defined. A back gap 110 and secondread gap 112 of electrically insulating, nonmagnetic materials such asalumina, silicon dioxide or diamond-like carbon are also formed.

A first pole layer 115 of magnetically permeable material such aspermalloy is then formed for transducer 40, layer 115 also serving as ashield for the MR sensor 44 in this example of a merged head. Note thatin other embodiments greater separation of the MR transducer 44 and theinductive transducer 40 may be desirable. A nonmagnetic, electricallyinsulating write gap 118 of material such as alumina, silicon dioxide ordiamond-like carbon is formed on the pole layer, and a conductive coil120 is formed on the write gap 118, the coil surrounded by nonmagnetic,electrically insulating material 122 such as baked photoresist.Conductive leads 56 and 58 connect with the coil 120 to provide currentfor inducing a magnetic flux across recording gap 118, the leads alsohelping to define dimensions for the gimbal, as will be shown below. Asecond pole layer 125 of magnetically permeable material is then formed,and a protective coating 127 of alumina, DLC or other materials isconventionally formed. The protective coating may be formed to athickness allowing gimbals 35 that are subsequently defined to containonly thin film materials. Other known transducers may be formed insteadof the above example of a merged head.

The substrate and thin film layers are then cut along a number of linessuch as lines 130 and 133, forming for example one hundred rows of headsfrom a single wafer 100. FIG. 5 shows row 140 cut from the substrate100, with the recently formed inductive transducer 40 and leads 56 and58 visible through the transparent protective coating. The wafer 100thickness T will determine the length of the integrated head and flexure30 of row 140 and all other rows. Processing of row 140 then occurs onsurfaces 130 and 133, both of which may be lapped to thin and smooth thehead and flexure 30. Surface 130 is lapped while resistive leads aremonitored to obtain a desired height of transducers 40 and 44. Thepolished row 140 has a height H which may be about 100 microns in thisexample, but which may be tailored to significantly different heightsdepending upon desired implementations. After lapping, surfaces 130 and133 are masked and etched to form the desired media-facing surface,head, gimbal and flexure that are depicted in FIG. 1.

As shown in FIG. 6, all of surface 130 is exposed to etching, preferablyby ion beam etching (IBE) or reactive ion etching (RIE), except forphotoresist or other masking that covers rails 48 and 49 and pad 50,while rails and pads of other heads of row 140 are covered by similarmasks, not shown. After the rails 48 and 49 and pad 50 have been formed,which project from the rest of the media-facing surface of the head onthe order of a micron, a thick mask is formed over the head 33 and otherheads of the row 140, as shown in FIG. 7.

A multimicron, highly anisotropic etch is then performed that removesthe suspension flexure and gimbal from the media-facing surface of thehead 33. This etch, preferably performed by RIE, removes a substantialfraction of the row 140 height H between surfaces 130 and 133, except inthe area of the head 33 which is covered by the thick mask. As known inthe art of MicroElectroMechanical Systems (MEMS) such etching can havehigh aspect ratios of perpendicular versus lateral etching, so that tensof microns of etching in the Z-direction may be accomplished with lessthan one micron of etching in the X-direction or Y-direction. Exactcontrol of the depth of etching in the Z-direction may be accomplishedby timing or by monitoring the etching process for evidence ofconductors 56 and 58, which have been formed to a distance predeterminedto serve as an etch-stop signal. A protective coating of diamond-likecarbon (DLC), tetrahedral amorphous carbon (ta-C), silicon carbide (SiC)or the like may then be formed on the rails 48, 49, pad 50, gimbal 35and flexure 38. For the situation in which such a protective coating wasformed over the media-facing surface prior to defining pads 48, 49 and50, the head 33 may not be coated again.

The row 140 is then turned over to work on surface 133, which willbecome a back surface, as shown in FIG. 8. If conductors 56-59 have notalready been exposed by lapping of this surface, etching can beperformed until evidence of these conductors occurs, determining heightH with precision. Conductors 56-59 or other marks created duringformation of transducer layers can also be used as guides for preciselyaligning the features on both sides of the row 140. The protrusion 88that will serve as a fulcrum for the head 33 can be formed at this timeby masking an area over the protrusion and etching away other areas ofthe back surface of the head. Sloping sides of the protrusion 88 can beformed by rotating IBE or other forms of at least somewhat isotropicetching know in the art of magnetic head fabrication. Alternatively, theprotrusion 88 may be formed by deposition of material such as ceramic ormetal that matches the material of the head or tongue 85, or bydeposition of extremely hard materials such as DLC, SiC or ta-C.

The head 33, flexures 38 and gimbals 35 are then covered with a thickmask, and a multi-micron perpendicular etch is performed on row 140 thatdefines a U-shaped aperture between those elements. Conductors 52-55 andpads 74-77 are then formed, for example of gold (Au), copper (Cu),beryllium copper (BeCu) or aluminum (Al). A protective insulativecoating is then formed, except over pads 74-77. Individual device 30 maybe severed from other devices at this point by cutting or furtheretching.

The device 30 may be connected to the load beam 80 by various methods.Epoxy bonding can be used for mechanical connection, for example, whilewire bonding or stitching can provide electrical connections betweenpads 74-77 and electrical leads formed on a non-media-facing side of theload beam. Alternatively, ultrasonic bonding may be used to connect pads74-77 with electrical leads formed on a media-facing side of the loadbeam. Distancing such bonding from the head and gimbal area removesmechanical uncertainties and complexities from the most sensitive areaof device 30, in contrast with conventional head and gimbal connectionmechanisms.

FIG. 9 shows a disk-facing side of another embodiment of the presentinvention, in which a device 150 including a head 152, gimbal elements155 and flexures 158 may be formed from less wafer real estate than thatused for a conventional pico-slider. The head 152 has a generallytriangular disk facing surface 160 with rails 162 and 164 and pad 166projecting slightly. An inductive transducer 170 and a MR transducer 171are visible through a transparent protective coating on pad 166, withthe inductive transducer disposed in a slightly projecting area 174compared to the MR transducer. This slight difference in elevationbetween the inductive transducer 170 and the MR transducer 171, whichmay be on the order of 100 Å, allows the former to write at highresolution while the latter avoids thermal asperities and wear that mayotherwise be caused by operational contact with the disk. Conductiveleads 180 and 181 connect with the inductive transducer 170 while leads182 and 183 connect with the MR transducer 171, the leads formed alongwith the transducers and exposed during etching of the gimbal elements155, the exposure signaling completion of etching the gimbal elements. Abase 188 is formed to provide mechanical and electrical connections forthe device.

FIG. 10 shows a non-disk-facing side of device 150, connected to a loadbeam 200. The gimbal 155 and flexure 158 elements have also been etchedor ablated from this side to the point at which conductors 180-183 areexposed, so that those suspension elements are not coplanar with anon-disk-facing 190 surface of the head 152. As can be seen in FIG. 11,this allows the suspension elements including flexure 158 to be locatedcloser in height to the center of mass of the head 152. Aligning theheight of suspension elements closer to the center of mass of the headreduces torque that would otherwise occur during rapid movement of thehead from one disk track to another, during which time the headexperiences extreme acceleration and deceleration. As described above, aprotrusion that can act as a fulcrum may optionally be formed on surface190.

Conductive leads 192 and 193 are formed along flexures 158 connectinginductive transducer leads 182 and 183 with pads 196 and 197,respectively. Similarly, conductive leads 194 and 195 are formed alongflexures 158 connecting MR transducer leads 180 and 181 with pads 198and 199, respectively. After masking the head 152, gimbal 155, flexure158 and base 188, the non-disk-facing side is etched or ablated again tocreate voids and separate device 150 from adjacent devices.

Device 150 is then connected to load beam 200, which has short tongue205 that bonds with a central portion of base 188, as shown additionallyin FIG. 11. An amplifier chip 210 is attached to the beam 200 andextends onto the tongue, the chip having a number of bond pads 212. Bondpads 196-199 of the device are connected to bond pads 212 of the chip,for example by wires 215.

In FIG. 12, load beam 200 is made of layers 201 and 202, with layer 201having a tongue 206 that extends over head 152 to provide protection anda shock-absorbing backstop for the head in the event of a shock to thedrive. An amplifier chip 211 is attached to layer 201 on one side oftongue 206, layer 201 being attached to a pedestal 218 of device 150. Asimilar chip may be attached on the same side of another arm sharing thespace between disks, not shown, so that the chips are offset and avoideach other. Wires 213 and 214 provide electrical connections betweenchip 211 and leads on the device 150 and beam 200, respectively.

As shown in FIG. 13, conductive leads need not span the gimbals in theZ-direction in order to define etch stops for the gimbals. For instance,MR transducer leads 182 and 183 can define an etch stop for thenon-disk-facing side of the gimbals 155 while inductive transducer leads180 and 181 can define an etch stop for the disk-facing side of thegimbals, with a connector leading to the non-disk-facing side. Timingcan be employed to control the extent of etching in addition to orinstead of monitoring for etch stop materials.

Beginning with FIG. 14, a head 200 is illustrated that includes atransistor amplifier 201 formed adjacent to the read and writetransducers. A pair of write leads 202 and 204 are connected to a coil,not shown, of an inductive transducer 210. A pair of sense leads 212 and214 are connected to a MR transducer, which is disposed behind theinductive transducer and therefore not shown in this figure for clarity.Amplifier leads 215 and 217 extend adjacent to sense lead 214, andterminate at source electrode 220 and drain electrode 222, respectively.Sense lead 214 is connected to a gate electrode 225 that is disposedover a semiconductor region forming a gate for transistor 201. Sourceelectrode 220 and drain electrode 222 are disposed over source and drainregions having opposite conductivity type to that of the gate. Amechanism such as a resistor is disposed in series with lead 214 distalto the MR transducer and optionally on the head, so that changingresistance in the MR transducer responsive to a signal from the mediachanges the voltage on gate electrode 225. This change in voltage on thegate electrode may be amplified on the order of 100 times in theamplifier leads. Note that this simple example of a single transistor201 may be supplanted by a CMOS transistor, known amplifier and/ordetector circuits. Examples of detector circuits that may be formed onthe head are described in U.S. Pat. Nos. 5,546,027, 5,430,768 and5,917,859, incorporated by reference herein, for which some electronicssuch as clock generators may be provided separately, for instanceadjacent the load beam or actuator. Perhaps one thousand square micronsof chip real estate may be available on the trailing edge of head 200for formation of amplifier and/or detector circuits.

FIG. 15 shows some initial steps in the formation of the head of FIG.14. On a preferably silicon wafer substrate 250 that will eventually bepatterned to form a head and flexure, a P-type semiconductor layer 252is formed. In an alternate embodiment the wafer may be doped P-type orN-type and layer 252 need not be formed, as known in the art ofintegrated circuit fabrication. An oxide layer 255 is grown onsemiconductor layer 252, masked and etched, leaving an area of theP-type layer 252 upon which a gate oxide layer 257 is formed. A dopedpolysilicon gate 260 is formed atop gate oxide 257 and both are trimmedto leave areas for N-type, self-aligned source 262 and drain 266 to beformed by ion implantation. The wafer may after ion implantation beannealed at temperatures exceeding 500° C., as known in the art ofcircuit fabrication.

In FIG. 16, another oxide layer has been formed, masked and etched tocreate dielectric regions 270, leaving gate 260, source 262 and drain266 exposed, upon which gate electrode 225, source electrode 220 anddrain electrode 222 are respectively formed. Another dielectric layer277 is then formed, for example of SiO₂, creating a smooth planarsurface for subsequent formation of a magnetic shield layer, not shownin this figure. A via may be etched in this layer 277, the via thenbeing filled with conductive material to form an electrical interconnect280 between gate electrode 225 and sense lead 214. Additionalinterconnects may be stacked on interconnect 280 to complete aconductive path to sense lead 214 through a dielectric layer formedadjacent the first shield and first read gap layer. Note that thepreceding description of a most basic transistor amplifier can beextrapolated to the formation of much more complicated circuits, any ofwhich may be included in a head of the present invention.

FIG. 17 shows a transducing device 300 including a head 303 integratedwith flexure 305 and gimbal 308 elements. The device 300 has been formedon and patterned from a ceramic substrate such as a silicon wafer, muchas described above. The head 303 has a media-facing surface with threeprojections, pads 310, 313 and 315, which are designed for contact ornear contact with a rapidly moving media surface such as that of a rigiddisk. Since head 303 does not have large air bearing surfaces such asrails, the head can be very small and light, so that the device 300 maybe significantly smaller than a pico-slider. The pads 310, 313 and 315may project from a recessed area 318 of the media-facing surface bybetween about a micron and ten microns, and are preferably coated withan extremely hard, wear resistant coating such as DLC, ta-C or SiC. Aninductive transducer 320 has poletips terminating on or adjacent anexposed surface of pad 310 for close proximity to the media, so thatsharp and strong magnetic patterns can be written on the media. A MR orGMR transducer 322 terminates adjacent to a recessed portion 325 of pad310 that avoids contact with the media even when the remainder of pad310 contacts the media, so that a read transducer 322 such as a MR orGMR sensor avoids wear and thermal asperities, as described in U.S. Pat.No. 5,909,340, incorporated by reference herein.

The flexure 305 and gimbal 308 may have a non-media-facing surface thatis generally coplanar with a non-media-facing surface of the head,simplifying removal of material from the non-media-facing side. Theflexure 305 and gimbal 308 may instead have a media-facing surface thatis generally coplanar with the recessed area 318 of the head, in orderto align the flexure and gimbal with dynamic forces of the head/mediainterface. The head 303 may contain amplifier circuitry, and conductiveleads may be formed along the non-media-facing sides of flexure 305 andgimbal 308 elements, as described above.

Alternatively, as shown in FIG. 18, the flexure 305 and gimbal 308 mayhave a different Z-height than both major surfaces of the head, so thatthe flexure and gimbal are flexible in the Z-direction as well asaligned with the Z-height of the center of mass of the head, reducingtorque during seek and settle operations. The device in this example hasa pair of pedestals 330 and 333 that have a similar Z-height as thesurface of the head 303 facing away from the media, the pedestals beingattached to a laminated load beam 335, which may contain stainless steelfor strength and convenience. Instead of forming separate pedestals forbonding to the load beam, the device may have a continuous plateaudistal to the transducers for attachment to the load beam. An amplifierchip 340 is disposed on the load beam and electrically connected to thedevice and beam by wires 357 and 366, respectively. The load beamincludes a lower layer 346 that is bonded to pedestals 330 and 333, andan upper layer 348 that extends over the head 303 in a loop 350, as seenin the top view of FIG. 19.

Also apparent in FIG. 19 are a plurality of electrical conductors 352leading between the head and a corresponding plurality of contact pads355 disposed on device 300 near pedestals 330 and 333. Wires 357 connectpads 355 with input/output pads 360 on chip 340. Additional input/outputpads 363 on chip 340 are connected by other wires 366 to electricalconductors 370 disposed on load beam 335 and leading to drive circuitry,not shown. More or less pads and conductors may be employed dependingupon the desired implementation, and conductors 370 are separated fromconductive material of the load beam 335 by dielectric material, or loadbeam may be dielectric.

FIG. 20 shows a device 400 including a piezoelectric layer 404 that maybe employed to help position the device. Much of device 400 is likedevice 30 shown in FIG. 1, and so for brevity substantially similarelements will not be renumbered or discussed at this point. Much asabove, device 400 is formed on and from a wafer substrate, but prior toformation of head elements on a major surface 401 of the wafer, aconductive layer 408 is formed on a major surface 402 of the wafer. Theconductive layer 408 may be formed of a metal or conductive ceramic thatadheres well to the wafer and to the piezoelectric layer 404 that isformed atop the conductive layer. The piezoelectric layer 404 may bemade of lead zirconium titanate (PZT) or other solid materials known tochange shape in response to an electric field, a phenomenon known aselectrostriction or the inverse piezoelectric effect, including ceramicssuch as barium titanate, many of which have a perovskite crystallinestructure. Dielectrics such as alumina or silicon dioxide also exhibit asmall amount of electrostriction, which may be sufficient to formactuators for certain applications, particularly if multiple thin(typically submicron layers are sandwiched between electrodes. For thesituation in which the piezoelectric layer 404 is made of PZT, layer 404may have a thickness in a range between less than a micron and more thanten microns, depending in part on the amount of positioning desired tobe accomplished with the layer 404 and the voltage available to controlthat positioning.

For the case in which a material such as PZT is used to form layer 404,applying heat and an electric field may control the direction of theelectrostrictive expansion or contraction of that layer during operationin response to an electric field. For example, the wafer and layers 404and 408 may be heated to an elevated temperature, such as 700° C. toover 1000° C., with an electric field provided between layer 408, whichserves as a first electrode, and a second electrode held adjacent asurface 410 of the piezoelectric layer 404, which may also provide heatfor the annealing. An isolation layer may be provided on layer 404 toallow separation of the second electrode after annealing. Heat forannealing may optionally be provided by initially supplying analternating electric field between the first and second electrodes.After cooling and cleaning the wafer, the head elements are formed on anopposite surface 401 of the wafer from layer 404, followed by separatingthe wafer into rows and working the rows to create the media-facingsurfaces, heads, flexures and leads, much as described above.

A base portion 414 of the substrate, conductive layer 408, andpiezoelectric layer 404 retain a greater Z-direction thickness thanflexures 38, for attachment to a load beam 420, as shown in FIG. 21.Referring additionally to FIG. 22, the load beam in this embodiment islaminated, with a first layer 422 having a similar thickness aspiezoelectric layer 404, for abutting layers 404 and 422. A second layer425 of the load beam sits atop layer 422 and terminates at substantiallythe same plane 423 as layer 422 for sections that are joined topiezoelectric layer 404. A tongue 428 of layer 425 extends beyond theend of first load beam layer 422, providing a guide for joining layer422 to piezoelectric layer 404. Tongue 428 may optionally be attached tolayers 404, 408 and/or base portion 414, providing increased support ata location subject to minimal electrostrictive induced movement. Layer425 also separates the device 400 from a third load beam layer 430,except at protrusion 88, which may contact beam layer 430 duringoperation.

Conductive pads 434-437 are connected by wires 450 to conductive pads444-447, respectively, which in turn are connected to leads 454-457disposed on layer 425, allowing signals to pass between the transducersand drive electronics. Also disposed atop layer 425 are leads 458 and459, which terminate in electrodes 452 and 455 respectively, whichprovide signals for positioning device 400. Such signals may be providedby drive electronics after processing the sensing by transducer 44 ofservo markings in a media. In an embodiment in which leads 454-459 areformed on a polyamide layer, that layer may be folded to adhereelectrodes 452 and 455 to the end of load beam layer 425. Providingincreased support is a nonconductive central plate 460 that hassubstantially the same thickness as electrodes 452 and 455, helping tojoin the end of layer 422 with device end surface 420. Plate 460 andelectrodes 452 and 455 may be attached to piezoelectric layer 404, firstbeam layer 422 and optionally second beam layer 425 with epoxy or otherknown bonding techniques. The distance between electrodes 452 and 455may be greater than twice the distance between those electrodes andconductive layer 408.

Conductive pads 434-437 may be disposed on base portion 414 so as tominimize any mechanical effect on flexures 38 from wires 450. For thisembodiment in particular, conventional twisted wires held by tubes orbends along lateral edges of layer 430 may replace conductive trace orprinted circuit board leads 454-459. In such an embodiment, electrodes452 and 455 may be separate metal plates that are attached to the endlayer 422, in which case layer 425 may extend less than layer 422 exceptat the tongue, leaving room for bonding of leads 458 and 459 toelectrodes 452 and 455, respectively. In another implementation, endplane 423 may be formed by bending tabs of layer 425, eliminating theneed for layer 422.

FIG. 23 illustrates the actuation of device 400 in response to signalsV1 and V2 from the drive electronics, applied to electrodes 452 and 455.In order to focus on this aspect of the invention, only major featuresof device 400, such as head 33, flexures 38 and read element 44, areshown. Conductive layer 408 forms a common electrode oppositepiezoelectric layer 404 from electrodes 452 and 455, so that when V1 isdifferent than V2 one side of layer 404 expands and the other sidecontracts. This expansion and contraction of layer 404 causes device 400to essentially pivot relative to plate 460, so that read element 44moves as shown by arrow 470 to the location of 44′. The amount oflateral motion provided by this mechanism can be controlled by voltagesV1 and V2, with the layer 404 expansion and contraction magnified by thelength of the device from central plate 460 to read element 44 ascompared to the distance between electrodes 452 and 455. In conjunctionwith a conventional voice coil actuator and servo controls, not shown,device 400 can be positioned over media tracks with an error of lessthan 50 nm.

As can be understood by comparing FIG. 23 with FIG. 21, flexures 38 aredisposed substantially in a plane, and are preferentially stiff in alateral or in-plane direction, and preferentially flexible in anout-of-plane or Z-direction. Because the motion induced by changing thedimensions of piezoelectric layer 404 is essentially confined to thein-plane direction of flexure 38, low frequency vibrations due toactuation are greatly reduced. Unlike other proposed microactuators,solid state device 400 does not include elements that interfere withflexure and gimbal mechanics, such as devices that rotate a headrelative to an attached flexure or provide significant actuation in apreferentially flexible suspension direction. And unlike some proposedmicroactuators that move a laterally stiff plane of a flexible elementaway from the mass of the head, device 400 better aligns a laterallystiff plane of flexures 38 with the center of mass of the head 33.

FIG. 24 and FIG. 25 show another solid state device 500 including head,preferentially flexible elements and microactuator features. Device 500is like device 300 shown in FIG. 17, and so for brevity elements thatare similar between the two devices will not be described again. Device500 is formed on and from a wafer substrate, which may for example becomposed of silicon, alumina or Al₂O₃TiC, beginning with formation of aconductive layer 502 on a first major surface of the wafer. Conductivelayer 502 may be composed of various metals or ceramic materials thatare strong, adhere well to the substrate and survive potential annealingof a subsequently formed piezoelectric layer 505. Piezoelectric layer505 is then formed atop conductive layer 502 to a thickness that may forexample be in a range between about one micron and a few tens ofmicrons, followed by annealing with an electric field provided betweenconductive layer 502 and an electrode, not shown, that may also providethe heat for annealing. After cooling and cleaning the wafer, the headelements are formed on an opposite surface of the wafer from layer 505,followed by separating the wafer into rows and working the rows tocreate the media-facing surfaces, heads, flexures and leads, much asdescribed above.

Gimbal elements 508 may be formed entirely of thin films in thisembodiment, and a number of apertures 510, 512 and 515 are formed alongthe length of the device, separating flexures 520. Aperture 515separates conductive layer 502 into device electrodes 522 and 525. Forclarity in displaying other elements, leads disposed on gimbals 508 andflexures 520 than connect with read 322 and write 320 elements are notshown in this figure. Device 500 may have a length, based primarily uponthe thickness of the wafer, that is at least several times as long asthe distance between electrodes 522 and 525. For example, device 500 mayhave a length that is about four millimeters and a width that is aboutone-half millimeter.

Piezoelectric layer 505 is bonded to beam electrodes 530 and 533 andnonconductive central plate 535, which are in turn bonded to a flat end536 of a first layer 538 of a laminated load beam 540. A second beamlayer 544 terminates at least as far from head 303 as the first beamlayer 538, except for a tongue 546 which extends beyond end 536. Centralplate 535 and a central portion of piezoelectric layer 505 may be bondedto tongue 546. A third beam layer 550 is separated from the first beamlayer 538 by the second beam layer 544, the third beam layer extendingin a loop 555 that overlaps the head 303. Beam 540 leads that connectwith device 500 leads, both not shown in this figure, may be disposed onsecond beam layer 544 or may be held by tabs or in tubes of third beamlayer 550. Beam 540 leads that supply charge and voltage to electrodes522, 525, 530 and 533 may also be held by either second 544 or third 550beam layers. In an alternative embodiment, electrodes 530 and 533 andnonconductive central plate 535 may extend in parallel to form firstbeam layer. A base portion 560 of device 500 has a greater thicknessthan flexible elements 508.

Having four electrodes 522, 525, 530 and 533 arranged as shown in FIG.24 affords greater control of the piezoelectric expansion andcontraction of layer 505, which is magnified by the geometry of device500. For the case in which electrodes 522 and 533 are provided withmatching voltages and electrodes 525 and 530 are provided with adifferent matching voltages, a smoothly graded electric field existsacross piezoelectric layer 505, causing contraction of one side of layer505, expansion of the other side of that layer and neither contractionnor expansion at a midpoint of the layer. In conjunction with another,larger scale actuator that positions load beam 540, the microactuatorformed by electrodes 522, 525, 530 and 533 and piezoelectric layer 505may be used for damping and settling of vibrations, for stictionrelease, and for positioning of transducer 322 with an accuracy of lessthan 50 nm.

FIG. 26 illustrates some initial steps in the formation of a laminatedpiezoelectric microactuator that may be attached to any of the head,flexure and conductor devices previously described, in similar fashionas device 500 shown in FIGS. 24 and 25. A wafer substrate 600 has afirst conductive layer 602 formed on an opposite major surface from thaton which head elements will later be formed. A first piezoelectric layer604 is formed on the first conductive layer 602, followed by a secondconductive layer 606, a second piezoelectric layer 608, a thirdconductive layer 610, and a third piezoelectric layer 612. Thepiezoelectric layers 604, 608 and 612 may be deposited or laid as a PZTtape or gel that is malleable until annealed.

To orient the inverse piezoelectric expansion and contraction of layers604, 608 and 612, a conductive plate 614 is held adjacent to thirdpiezoelectric layer 612 and leads are connected to conductive layers602, 606, and 610 to provide high and low relative voltages, asindicated by the plus and minus signs, while the layers are annealed atan elevated temperature. Alternatively, another electrode layer can bedeposited on layer 612, that layer later divided in the removal processthat divides layers 604 and 608. A small portion of conductive 602, 606,and 610 may be left exposed in different areas near the perimeter of thewafer to afford electrical connection during polling. Upon cooling,layer 608 has a piezoelectric orientation opposite that of layers 604and 612. As a result, subsequent application to conductors 602, 606, 610and 614 of voltages similar to that shown, where a first voltage isinterspaced with a different second voltage, causes piezoelectric layers604, 608 and 612 to expand or contract in unison.

FIG. 27 shows a base portion of a head, flexure and conductor device 660formed on and from the wafer substrate 600, including piezoelectriclayers 604, 608 and 612. An aperture 616 has been formed that dividesthe conductive layers shown in FIG. 26 into individual electrodes 620,622, 624 on the left side of aperture 616, and individual electrodes630, 632 and 634 on the right side of aperture 616. Joined topiezoelectric layer 612 are first and second conductive plates, 640 and642, which also serve as electrodes, and a nonconductive central plate646. Wire or other conductive lead 650 electrically connects electrodes620 and 624, and a similar wire or other conductive lead 654electrically connects electrodes 630 and 634. Similarly, wire or otherconductive lead 652 electrically connects electrodes 622 and 640, and asimilar wire or other conductive lead 656 electrically connectselectrodes 632 and 642. Plates 640, 642 and 646 are joined to or may bepart of a load beam, not shown in this figure, and a central portion ofpiezoelectric layer 612 is joined to a tongue portion of that load beam.

Providing a first voltage to electrodes 620, 624, 632 and 642 whileproviding a different second voltage to electrodes 622, 640, 630 and 634causes piezoelectric layers 604, 608 and 612 on the left side ofaperture 616 to expand or contract relative to piezoelectric layers 604,608 and 612 on the right side of aperture 616, which causes a headdisposed on an opposite end of device 660 from layer 612 to move to theright or left. Forming plural piezoelectric layers oriented as describedabove allows the multiple electrodes to expand or contract thepiezoelectric layers by providing a single, relatively low level voltagedifference that expands the piezoelectric layers on one side in unisonwhile contracting the layers on the other side in unison, magnifying theelectrostriction effect for a given voltage difference.

FIG. 28 shows a top view of an actuator 700 for which a number ofelectrostrictive layers 702, 704, 706 and 708 and electricallyconductive layers 712, 714, 716 and 718 have been formed on a wafersubstrate 710 as described above. An insulating base layer 722 has alsobeen formed, after which an electromagnetic head or other device that isto be positioned by actuator 700 may be formed. Serpentine edges 725,726 and 272 are then formed that allow conductive leads 730, 732, 734and 736 to connect with alternate electrically conductive layers 712,714, 716 and 718. Conductive leads 730, 732, 734 and 736 are alsoconnected to electrodes 740, 742, 744 and 746, respectively, which areinterspersed with insulators 750, 752 and 754. Application of adifferent voltage to lead 730 compared to lead 732 and to lead 734compared to lead 736 causes an end of actuator 700 distal to layer 722to move laterally. Alternatively, electrical leads similar to leads 730,732, 734 and 736 may be formed in a zigzag or serpentine pattern toconnect with alternate conductive layers, and the conductive layers andelectrostrictive layers may be defined to have substantially straightedges. This embodiment may be advantageous for the case in whichelectrostrictive layers 702, 704, 706 and 708 are formed of submicronlayers, e.g., of silicon dioxide.

Although this disclosure has focused on teaching the preferredembodiments of the invention claimed, other embodiments andmodifications of this invention will be apparent to persons of ordinaryskill in the art in view of these teachings. For example, whileillustrated as employed in information storage and retrieval devices,the solid-state microactuators of the present invention may be used inmany other disparate applications. Therefore, this invention is limitedonly by the following claims and their equivalents, which include allsuch embodiments and modifications when viewed in conjunction with theabove specification and accompanying drawings.

1. A device for reading or writing information, the device comprising:an electromagnetic transducer including a plurality of solid transducerlayers, a substrate adjoining said transducer, said substrate shaped asa rigid body adjacent to said transducer and as a plurality of flexibleelements distal to said transducer, and an actuator attached to saidsubstrate distal to said transducer, wherein said actuator includes alayer of piezoelectric material, and said transducer layers aresubstantially parallel with said layer of piezoelectric material.
 2. Adevice for reading or writing information, the device comprising: anelectromagnetic transducer including a plurality of solid transducerlayers, a substrate adjoining said transducer, said substrate shaped asa rigid body adjacent to said transducer and as a plurality of flexibleelements distal to said transducer, and an actuator attached to saidsubstrate distal to said transducer, wherein said flexible elements aresubstantially aligned with a center of mass of said rigid body.
 3. Adevice for reading or writing information, the device comprising: awafer substrate piece disposed between an electromagnetic transducer andan electrostrictive actuator, said substrate piece shaped as a rigidbody adjoining said transducer and as a flexible element connecting saidrigid body and said actuator, wherein said actuator includes a layer ofpiezoelectric material, and said transducer includes a plurality oflayers that are substantially parallel with said layer of piezoelectricmaterial.
 4. A device for reading or writing information, the devicecomprising: an electromagnetic transducer including a plurality of solidtransducer layers, a substrate adjoining said transducer, said substrateshaped as a rigid body adjacent to said transducer and as a plurality offlexible elements distal to said transducer, and actuation means forpositioning said transducer, said actuation means attached to saidsubstrate distal to said transducer.
 5. The device of claim 4, whereinsaid flexible elements extend substantially parallel to a first planeand said transducer layers are substantially parallel to a second planethat is perpendicular to said first plane.
 6. The device of claim 4,wherein said transducer layers include a plurality of active layers thatconvert a magnetic signal to an electrical signal, said active layersseparated from said substrate by a plurality of inactive layers that donot convert between magnetic and electrical signals.
 7. A device forreading or writing information, the device comprising: anelectromagnetic transducer including a plurality of solid transducerlayers, a substrate adjoining said transducer, said substrate shaped asa rigid body adjacent to said transducer and as a plurality of flexibleelements distal to said transducer, and an actuator attached to saidsubstrate distal to said transducer, wherein said transducer layersinclude a plurality of active layers that convert a magnetic signal toan electrical signal, said active layers separated from said substrateby a plurality of inactive layers that do not convert between magneticand electrical signals.
 8. A device for reading or writing information,the device comprising: a wafer substrate piece disposed between anelectromagnetic transducer and an electrostrictive actuator, saidsubstrate piece shaped as a rigid body adjoining said transducer and asa flexible element connecting said rigid body and said actuator, whereinsaid transducer includes a plurality of active layers that convert amagnetic signal to an electrical signal, said active layers separatedfrom said substrate by a plurality of inactive layers that do notconvert between magnetic and electrical signals.